I have vouchers that are expiring in the near future and I'm trying to maximize the MQMs I can earn over a long weekend using those vouchers. I found a routing on ITA that has two Delta segments and six KLM segments, but when I try to book on DL.com those KLM flights are not an option.

Will I be able to book those flights over the phone with Delta? I wanted to ask here before I call so I know what to expect from the agent. If that won't work, is there any way to use the Delta credits and book directly with KLM? I found an old thread about using a KLM voucher for a Delta booking but I didn't see anything about the reverse.